This invention relates to machines for picking various farm crops and is concerned more specifically with constructions of pickup conveyers.
The invention can be applied in constructions of conveyer pickups used for picking various farm crops both windrowed and spread.
Most extensive application has been gained by the pickup conveyor constructions featuring bolted attachment of the spring-actuated double pickup fingers to the conveyer belt. A disadvantage of said attachment resides in a hampered dismantling of the pickup finger owing to the fact that the anticorrosive protecting coating on the exposed threaded bolt portion is liable to wear away in the course of operation, and the thread is liable to corrode which, in turn, prevents the nut from backing off and causes the bolt to turn along with the nut inasmuch as to retain the bolt head located above the conveyer belt proves to be impossible. Thus, the pickup finger can be dismantled only after the belt has been removed from the conveyer or, at best, not until the conveyer is let to turn till assuming the position, wherein the bolt head rests upon one of the conveyer shafts.
One prior-art construction of the pickup conveyer is known, wherein the double spring-actuated pickup finger is fastened to the support element through a U-shaped plate holder which embraces the yoke-shaped interspring crosspiece of the finger and said support element at the front end of both, said support element being in somewhat raised position at the place of finger mounting in such a way that a gap is defined in between the conveyer belt and the support element. With its side projections the holder enters inside the finger springs. The holder is locked in place due to engaging of a hole provided at the center of the raised portion of the support element, by a spherical lug provided on the holder, said engagement occurring by virtue of elastic forces. The support element is secured on the belt by means of riveted joints. The afore-discussed construction, however, suffers from a number of disadvantages. Thus, for instance, said riveted joints are inadequately reliable; when picking the reaped crop mass asymmetric load occurs upon the pickup fingers, whereas the U-shaped plate holder performs its functions only in those cases where the point of the load application (or of application of the equivalent force of the loads applied at the finger ends) falls within the width of the holder crosspiece thrusting against the support element. If the load (or its equivalent force) is applied beyond the crosspiece a moment results that tends to turn the finger along with the holder with respect to the edge of the holder crosspiece, nearest to the point of the load application and to disengage the locking lug of the holder from the hole in the support element. Inasmuch as the locking force cannot be too high as otherwise the condition of easy detachability of the finger will not be met, it is quite obvious that unlocking (i.e., disengagement of the locking lug from the hole) is liable to occur under as low asymmetric loads applied. It is on the same account that the holder fails to perform its functions in the case of load reversal which might take place, e.g., when the farm machine travels backward.
The yoke-shaped interspring crosspiece of the pickup finger is made flat in a lateral projection both in the constructions with bolted attachment and in those with the U-shaped plate holder.
A disadvantage of such a construction of the crosspiece resides in great overstresses occurring in the material of the conveyer belt at the place of holding the pickup finger within the time space while the finger travels round the shaft. This is accounted for by the fact that the vertex of the flat crosspiece rises above the curved surface so that the load upon the finger is taken up by the belt over but a short attachment arm which equals half the bolt or rivet head diameter.